package per.n.p103;

import java.util.Scanner;

public class P103 {

    public static void main(String[] args) {
        var input = new Scanner(System.in);
        int tmp = input.nextInt();
        if(tmp <= 1)
        {
            System.out.println("1");
        }
        else
        {
            System.out.println(f(tmp - 1));
        }
        input.close();
    }

    public static int f(int index) {
        if (index!=1 && index!=2) {
            return f(index - 1) + f(index - 2);
        }
        else
        {
            return 1;
        }
    }
}
